Cover Picture: Astron. Nachr. 01/2023

Synthetic image of the accretion disk around the black hole at the center of the galaxy M87. The bright emission corresponds to the part of the disk approaching us. The simulation is based on the so-called pseudo-complex General Relativity (pcGR), an extension of the standard theory of General Relativity (GR) constructed to avoid singularities. At a spatial resolution of 20 μ arcsec (left image), comparable to the resolution of the Event Horizon Telescope (EHT) of 24 μ arcsec, the predictions of GR and pcGR are indistinguishable. Only at even higher spatial resolution, better than 5 μ arcsec (right image), the pcGR prediction of a dark ring followed further in by a bright ring could be revealed. For further details see the article by Maghlaoui and Hess, page e220067 in this issue.